The Census Bureau estimates that by the year 2030, there will be 70 million people aged 65 or older, more than twice the number in 1999. These older Americans represent just 13% of the population in the year 2000 but are expected to make up 20% of the population by 2030. Of particular concern in this aging society is the finding that many cognitive functions decline with normal healthy aging. Previous research has indicated that multiple factors are associated with these cognitive impairments, including deficits in the speed of processing, poorer self-initiated processing, reduced working memory capacity, lack of inhibitory control, and reduced perceptual processing. The multiple interactions among these possible causes make it difficult to isolate one particular process and nearly impossible to make predictions based on a purely verbal model. This proposal describes a program of research designed to assess the effects of reduced perceptual processing on memory functioning by looking at detailed error patterns among young and old participants in a wide variety of memory paradigms. These data will then be fit using two existing models of memory that have heretofore been used mainly with younger populations. Because the parameters of these models can be mapped on to each of the factors of interest (speed of processing, perceptual efficiency, etc.), it is possible to determine the relative contribution of each factor and, more importantly, see how these factors interact in a dynamic system. Given this analysis of the dynamic interactions among the factors, specific predictions about the types of tasks and situations which should and should not result in processing difficulties for older adults can be made and will be tested empirically. The long-term goal of these studies is to develop a formal, quantitative model that will allow researchers and practitioners to focus specifically on those areas of functioning that are critical to efficient cognitive processing. In addition, the studies will demonstrate that perceptual processing abilities must be considered and either controlled for or manipulated in cognitive aging research.